1-Based on past messages, PrEl will not run PROPERLY when installed on anything other than your boot drive... you should only put your video files on an external drive
2-More information needed for someone to help... click these links and provided the requested information
Adobe programs are not "portable," in that they do not run on HDD's, that are moved between various machines.
What was the intent of installing on an external?
One user, Neale, has installed onto his D:\ (internal HDD), and has not noted any issues, but then Adobe programs really like being installed on C:\. The Projects, media, Scratch Disks, etc., work fine on external HDD's, but the program is not likely to do so.
I would uninstall from the external, re-install to the C:\, and then use that external for Projects, etc.. This ARTICLE goes into more detail, that might be useful for you.
Bill Hunt wrote:
One user, Neale, has installed onto his D:\ (internal HDD), and has not noted any issues,
I'm a far greater heretic than that Bill
PRE is installed on my E: drive (the third partition of my first disk). Project files are on I: my second, non-partitioned physical drive. But, as you say, I have no issues with that setup.
Insanity is hereditary, you get it from your children
Once you have the program installed on your internal C drive, and your media on your external drive, you still need to know what KIND of video, so you may insure that your project matches your file
Read Bill Hunt on a file type as WRAPPER http://forums.adobe.com/thread/440037
What is a CODEC... a Primer http://forums.adobe.com/thread/546811
What CODEC is INSIDE that file? http://forums.adobe.com/thread/440037
Report back with the codec details of your file, use the programs below... a screen
shot works well to SHOW people what you are doing
For PC http://www.headbands.com/gspot/ or http://mediainfo.sourceforge.net/en
For Mac http://mediainspector.massanti.com/
If you have a red line over the timeline after importing a video and before adding any
effects... your project is wrong for your video... read above about codecs
Once you know exactly what it is you are editing, report back with that information...
and your project setting, and if there is a red line above the video in the timeline,
which indicates a mismatch between video and project